Meet Hans Herren, Organic Bug Killer Who Saved Africa From Famine

A mealybug on a cassava stem
A mealybug on a cassava stem
Pascaline Minet

GENEVA — Between a mission in Ethiopia and a meeting in Rome, Hans Herren stops over in Geneva to speak at a conference at the World Trade Organization. The Swiss agricultural engineer is a world-renowned expert in insects who has spent most of his professional life in Africa. During the 1980s and 90s, he established a massive program to combat an insect that destroyed yuca (also called manioc, or cassava) crops. The project is credited with averting famine for literally millions of people.

Herren, 66, now devotes most of his time promoting “green” agriculture techniques to the public and to politicians. For his efforts in that domain, he was awarded the 2013 Right Livelihood Award — also known as the “alternative Nobel Prize” — given to distinguished individuals who work on environmental or development issues.

Born in 1947, Herren grew up in Vouvry in southwestern Switzerland, where his father had a tobacco farm. He continued his studies in agricultural engineering at the Zurich Engineering School, where he specialized in entomology, the study of insects. Then he went to the University of California at Berkeley for two years to deepen his knowledge of organic insect control — an approach that consists of fighting agricultural pests with their natural predators, usually other insects.

“After my studies, I didn’t really feel like returning to Switzerland, because the opportunities for developing organic pest control systems seemed limited,” he remembers. “So I went to Africa, sort of looking for an adventure.”

Entomologist and agricultural engineer — Photo: WTO

When Herren arrived at the International Tropical Agriculture Institute in Nigeria, there was a major food security threat hanging over the continent. An insect called the cassava mealybug was attacking the tuber that provided most of the nutrition for 200 million Africans. The cassava mealybug was accidentally introduced to Africa by scientists, and didn’t have any natural predators in Africa — so it was spreading quickly. Insecticides didn’t work, and breeding a naturally-resistant variety of yuca would take years.

Good killer wasps

That’s the context in which Herren started his one-man battle against the mealybug that made him famous, and for which he was awarded the World Food Prize in 1995. First, the agricultural engineer and his colleagues tried to identify an insect in nature that was a natural predator of the mealybug.

“If such an insect existed, it would have to live in some part of Latin America, because that is the native region for yucas and for the mealybug,” he explained. After several unsuccessful attempts, the researcher finally found, in Paraguay, parasitic wasps that laid their eggs in the mealybugs’ abdomen and killed them.

They couldn’t just release the wasps in Africa without taking some precautions. The wasps were quarantined in a lab in London for several months, where Herren and his colleagues verified that they did in fact attack the cassava mealybug specifically, and that they didn’t carry viruses. “There is always a risk when you introduce a new species into an environment where it is not native,” Herren admitted. “But we carried out all possible experiments to minimize that risk.”

The first tests at the beginning of the 1980s, in infested fields in Nigeria, produced excellent results. A couple of months after the introduction of the natural enemies, the mealybug populations plummeted. They then stabilized, at a low level. Thanks to that experience, Herren convinced the Interafrican Phytosanitary Agency to deploy his wasps on a large scale over the entire continent.

That’s when another adventure started for the agricultural engineer. The areas infested by the mealybug were so vast that the wasp releases had to be done by airplane. These were often quite eventful: “We were shot at over Ghana, and another time, we were forced to land in Tanzania, because they thought we were spies,” Herren remembers with a grin.

Around 1.6 million wasps were released as part of the program, which lasted from 1982 to 1993 and covered 24 countries in the “yuca belt,” which extends from Senegal to Mozambique. Since then, populations of both the mealybug and the parasitic wasp have remained low and stable, making the project an undeniable success.

“The program developed by Hans Herren was based on a relatively classic concept in organic pest control, which is to introduce the natural enemy of the pest,” explained Marc Kenis, a researcher at CABI, a research center based in Delemont that specializes in organic pest control. “The impact he had on food security is especially notable.”

Nigerian farmers — Photo: Mike Blyth

In fact, according to the the World Food Prize Jury, Herren saved the life of around 20 million people with his project.

But Herren is modest about his accomplishments. “At the time, there was a problem with the mealybug, and I did my best to find a solution. I was particularly satisfied that we were able to prove that you can solve serious agricultural engineering problems with simple, environmentally friendly solutions,” he said.

A pilgrim's march

His experiences have made Herren a strong advocate of sustainable agriculture, based on agricultural techniques that respect the environment, like organic pest control, but also crop rotation and green fertilizer. He believes that the world urgently needs to turn its back on the agricultural techniques that took root in developed countries and some developing countries (such as India) after World War II. “That agriculture, based on large amounts of fertilizer and pesticides, has led to an increase in production but it has also caused serious pollution and has destroyed the soil fertility,” he explains.

Herren also refused to consider GMOs a solution for increasing crop yields, due to their cost and uncertainties about their effect on the environment. “It seems illogical to try to create new organisms, when we are not doing anything to protect the agricultural biodiversity that already exists and is disappearing rapidly,” he says.

Cassava production in Nigeria — Photo: USAID

Philipp Aerni, a specialist in agricultural policy and development at Herren’s alma matter in Zurich, who has been researching yuca varieties for several years, does not agree with Herren’s assessment. “Organic pest control worked well against the mealybug, that is true, but there are other pests against which that technique does not work. It is necessary to imagine other solutions, and I think that discarding biotechnologies out of principle is a mistake.” In fact, a research group at his university is developing a GMO yuca that would be resistant to certain viruses.

In 2005, Herren left his job as the director of the International Center for the Physiology and Ecology of Insects, based in Nairobi, Kenya, after working there for 11 years. Since then, he has worked full-time promoting sustainable agriculture, particularly through the Biovision foundation, which he started in 1998. Based in Zurich, Biovision works to promote the spread of sustainable agricultural techniques among small farmers in East Africa.

Herren was co-president of the International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD), an initiative that brought 400 researchers together for two years to discuss solutions to feeding the planet’s population.

The IAASTD’s report was made public in 2008, and the experts pointed to both organic agriculture and ecological agricultural methods as the routes to follow to guarantee the world’s future agricultural needs. “Why don’t the majority of countries follow this model of agricultural development, even though it is supported by the experts? Probably because of resistance from agricultural companies, who do not want the system to change,” Herren says.

But the entomologist refuses to get discouraged. He takes the time to relax when he can at the organic farm he owns in California with his American wife — then he picks back up the pilgrim's baton, and resumes his journey to promote sustainable agriculture around the world.

Keep up with the world. Break out of the bubble.
Sign up to our expressly international daily newsletter!
food / travel

The True Horrors Behind 7 Haunted Locations Around The World

With Halloween arriving, we have dug up the would-be ghosts of documented evil and bloodshed from the past.

Inside Poveglia Island's abandoned asylum

Laure Gautherin and Carl-Johan Karlsson

When Hallows Eve was first introduced as a Celtic festival some 2,000 years ago, bonfires and costumes were seen as a legitimate way to ward off ghosts and evil spirits. Today of course, with science and logic being real ghostbusters, spine-chilling tales of haunted forests, abandoned asylums and deserted graveyards have rather become a way to add some mystery and suspense to our lives.

And yet there are still spooky places around the world that have something more than legend attached to them. From Spain to Uzbekistan and Australia, these locations prove that haunting lore is sometimes rooted in very real, and often terrible events.

Shahr-e Gholghola, City of Screams - Afghanistan

photo of  ruins of Shahr-e Gholghola,

The ruins of Shahr-e Gholghola, the City of Screams, in Afghanistan

Dai He/Xinhua via ZUMA Wire

According to locals, ghosts from this ancient royal citadel located in the Valley of Bamyan, 150 miles northwest of Kabul, have been screaming for 800 years. You can hear them from miles away, at twilight, when they relive their massacre.

In the spring 1221, the fortress built by Buddhist Ghorids in the 6th century became the theater of the final battle between Jalal ad-Din Mingburnu, last ruler of the Khwarezmian Empire, and the Mongol Horde led by Genghis Khan. It is said that Khan's beloved grandson, Mutakhan, had been killed on his mission to sack Bamyan. To avenge him, the Mongol leader went himself and ordered to kill every living creature in the city, children included.

The ruins today bear the name of Shahr-e Gholghola, meaning City of Screams or City of Sorrows. The archeological site, rich in Afghan history, is open to the public and though its remaining walls stay quiet during the day, locals say that the night brings the echoes of fear and agony. Others claim the place comes back to life eight centuries ago, and one can hear the bustle of the city and people calling each other.

Gettysburg, Civil War battlefield - U.S.

photo of rocks and trees in Gettysburg

View of the battlefields from Little Round Top, Gettysburg, PA, USA


Even ghosts non-believers agree there is something eerie about Gettysbury. The city in the state of Pennsylvania is now one of the most popular destinations in the U.S. for spirits and paranormal activities sight-seeing; and many visitors report they witness exactly what they came for: sounds of drums and gunshots, spooky encounters and camera malfunctions in one specific spot… just to name a few!

The Battle of Gettysburg, for which President Abraham Lincoln wrote his best known public address, is considered a turning point in the Civil War that led to the Union's victory. It lasted three days, from July 1st to July 3rd, 1863, but it accounts for the worst casualties of the entire conflict, with 23,000 on the Union side (3,100 men killed) and 28,000 for the Confederates (including 3,900 deaths). Thousands of soldiers were buried on the battlefield in mass graves - without proper rites, legend says - before being relocated to the National Military Park Cemetery for the Unionists.

Since then, legend has it, their restless souls wander, unaware the war has ended. You can find them everywhere, on the battlefield or in the town's preserved Inns and hotels turned into field hospitals back then.

Belchite, Civil War massacre - Spain

photo of sunset of old Belchite

Old Belchite, Spain

Belchite Town Council

Shy lost souls wandering and briefly appearing in front of visitors, unexplainable forces attracting some to specific places of the town, recorded noises of planes, gunshots and bombs, like forever echoes of a drama which left an open wound in Spanish history…

That wound, still unhealed, is the Spanish Civil War; and at its height in 1937, Belchite village, located in the Zaragoza Province in the northeast of Spain, represented a strategic objective of the Republican forces to take over the nearby capital city of Zaragoza.

Instead of being a simple step in their operation, it became the field of an intense battle opposing the loyalist army and that of General Francisco Franco's. Between August 24 and September 6, more than 5,000 people were killed, including half of Belchite's population. The town was left in rubble. As a way to illustrate the Republicans' violence, Franco decided to leave the old town in ruins and build a new Belchite nearby. All the survivors were relocated there, but they had to wait 15 years for it to be complete.

If nothing particular happens in new Belchite, home to around 1,500 residents, the remains of old Belchite offer their share of chilling ghost stories. Some visitors say they felt a presence, someone watching them, sudden change of temperatures and strange sounds. The ruins of the old village have been used as a film set for Terry Gilliam's The Adventures of Baron Munchausen - with the crew reporting the apparition of two women dressed in period costumes - and Guillermo del Toro's Pan's Labyrinth. And in October 1986, members of the television program "Cuarta Dimensión" (the 4th dimension) spent a night in Belchite and came back with some spooky recordings of war sounds.

Gur Emir, a conquerer’s mausoleum - Uzbekistan

photo of Gur Emir (Tomb of Timur) i

Gur Emir (Tomb of Timur) in Samarkand, Uzbekistan

Chris Bradley/Design Pics via ZUMA Wire

The news echoed through the streets and bazaars of Samarkand: "The Russian expedition will open the tomb of Tamerlane the Great. It will be our curse!" It was June 1941, and a small team of Soviet researchers began excavations in the Gur-Emir mausoleum in southeastern Uzbekistan.

The aim was to prove that the remains in the tomb did in fact belong to Tamerlane — the infamous 14th-century conqueror and first ruler of the Timurid dynasty who some historians say massacred 1% of the world's population in 1360.

Still, on June 20, despite protests from local residents and Muslim clergy, Tamerlame's tomb was cracked open — marked with the inscription: "When I Rise From the Dead, The World Shall Tremble."

Only two days later, Nazi Germany invaded the Soviet Union, with the people of Samarkand linking it to the disturbing of Tamerlane's peace. Amid local protests, the excavation was immediately wrapped up and the remains of the Turkish/Mongol conqueror were sent to Moscow. The turning point in the war came with the victory in the Battle of Stalingrad — only a month after a superstitious Stalin ordered the return of Tamerlane's remains to Samarkand where the former emperor was re-buried with full honors.

Gamla Stan, a royal massacre - Sweden

a photo of The red house of Gamla Stan, Stockholm, Sweden

The red house of Gamla Stan, Stockholm, Sweden


After Danish King Kristian II successfully invaded Sweden and was anointed King in November 1520, the new ruler called Swedish leaders to join for festivities at the royal palace in Stockholm. At dusk, after three days of wine, beer and spectacles, Danish soldiers carrying lanterns and torches entered the great hall and imprisoned the gathered nobles who were considered potential opponents of the Danish king. In the days that followed, 92 people were swiftly sentenced to death, and either hanged or beheaded on Stortorget, the main square in Gamla Stan (Old Town).

Until this day, the Stockholm Bloodbath is considered one of the most brutal events in Scandinavian history, and some people have reported visions of blood flowing across the cobblestoned square in early November. A little over a century later, a red house on the square was rebuilt as a monument for the executed — fitted with 92 white stones for each slain man. Legend has it that should one of the stones be removed, the ghost of the represented will rise from the dead and haunt the streets of Stockholm for all eternity.

Port Arthur, gruesome prison - Australia

a photo of ort Arthur Prison Settlement, Tasmania, Australia

Port Arthur Prison Settlement, Tasmania, Australia

Flickr/Eli Duke

During its 47-year history as a penal settlement, Port Arthur in southern Tasmania earned a reputation as one of the most notorious prisons in the British Empire. The institution — known for a brutal slavery system and punishment of the most hardened criminals sent from the motherland— claimed the lives of more than 1,000 inmates until its closure in 1877.

Since then, documented stories have spanned the paranormal gamut: poltergeist prisoners terrorizing visitors, weeping children roaming the port and tourists running into a weeping 'lady in blue' (apparently the spirit of a woman who died in childbirth). The museum even has an 'incidence form' ready for anyone wanting to report an otherworldly event.

Poveglia Island, plague victims - Italy

a photo of Poveglia Island, Italy

Poveglia Island, Italy

Mirco Toniolo/ROPI via ZUMA Press

Located off the coast of Venice and Lido, Poveglia sadly reunites all the classical elements of a horror movie: plagues, mass burial ground and mental institute (from the 1920's).

During the bubonic plague and other subsequent pandemics, the island served as a quarantine station for the sick and anyone showing any signs of what could be Black Death contamination. Some 160,000 victims are thought to have died there and the seven acres of land became a mass burial ground so full that it is said that human ash makes up more than 50% of Poveglia's soil.

In 1922 a retirement home for the elderly — used as a clandestine mental institution— opened on the island and with it a fair amount of rumors involving torture of patients. The hospital and consequently the whole island was closed in 1968, leaving all the dead trapped off-land.

Poveglia's terrifying past earned it the nickname of 'Island of Ghosts'. Despite being strictly off-limits to visitors, the site has been attracting paranormal activity hunters looking for the apparition of lost and angry souls. The island would be so evil that some locals say that when an evil person dies, he wakes up in Poveglia, another kind of hell.

Keep up with the world. Break out of the bubble.
Sign up to our expressly international daily newsletter!